The pro-ethanol trade group Growth Energy said Tom Buis, its chief executive officer since its early days, has been named co-chairman of its board of directors. A former president of the National Farmers Union, Buis joined Growth Energy as its chief executive in February 2009, three months after the group was formed. Jeff Broin, founder of the largest U.S. ethanol maker, POET, is the other co-chairman of Growth Energy. In a statement, Buis said he will continue to be active on renewable-fuel issues in his new role.